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Beam Facility

The external neutron beam line at OSURR is able to deliver a relatively-clean, small-sized (< 30 mm diameter) thermal neutron beam to a workbench, where various instruments can be set up for detector evaluation and in-situ materials characterization. The neutron collimator consists of single-crystal sapphire and polycrystalline bismuth filters (providing fast neutron and gamma-ray filtration, respectively) followed by a parallel series of 3-cm apertures for collimation. The thermal-equivalent neutron flux is ~4x106 n/cm2/s at the sample position, which is an optical table upon which instrumentation may be set up for in-situ testing of radiation detectors or coupons may be set up for characterizing materials, and ~2x106 n/cm2/s in the high-vacuum chamber. See the facility fluxes page for present values. The cadmium ratio, which is defined as the ratio of the activities of bare and cadmium-covered gold foils detectors and which characterizes the epithermal and fast neutron contributions in the neutron spectrum, was measured to be 92.